The reciprocating-type electric shaver is currently available in a number of types, all of which have a common structural feature in that they comprises a casing of, for example, a cylindrical or rectangular box-like configuration having a longitudinal axis, and a cutter head mounted on one end of the casing. The cutter head employed in such electric shavers includes a stationary blade member in the form of a perforated metal foil, and at least one movable blade member comprised of an array of generally semi-circular blades and adapted to be reciprocatingly driven relative to the stationary blade member in a direction perpendicular to the direction in which the shaver is moved during hair cutting and also to the longitudinal axis of the casing. As a drive source for the movable blade member other than an electric rotary actuator, the use of an electromagnetic linear motor is disclosed in European Patent Publication No. A1-674979 which has been laid-open to public.
In the cutter head of the electric shaver of the type disclosed in the above mentioned European Patent Application, the movable blade member is adapted to be reciprocatingly driven relative to the stationary blade member by an electromagnetic linear actuator. The electromagnetic linear actuator includes an electromagnet and a permanent magnet fitted to a carrier of the movable blade member. The carrier of the movable blade member is floatedly supported by a leaf spring so as to define a magnetic gap between it and the electromagnet. This electromagnetic linear actuator is so designed that when an alternating current is applied to the electromagnet to alternately develop a magnetic force of repulsion and a magnetic force of attraction in the magnetic gap, the carrier of the movable blade member and, hence, the movable blade member itself can be reciprocated in a direction perpendicular to the longitudinal axis of the casing.
In the electric shaver of a type wherein the rotary actuator is used and the movable blade member is reciprocated in a direction perpendicular to a drive shaft of the rotary actuator, the use is necessitated of a motion translating mechanism for translating a rotary motion into a linear motion. On the other hand, the electric shaver utilizing the electromagnetic linear actuator does not require the use of such a motion translating mechanism and, therefore, has such advantages that a mechanical loss is relatively low and the efficiency of utilization of power is relatively high. In addition, elimination of the use of the motion translating mechanism makes it possible to reduce the size of the electric shaver.
On the other hand, a generally elongated slender electric shaver particularly for use in treatment of human body hairs such as downy hairs and eyebrows has been made available in the market. This electric shaver comprises a generally cylindrical casing, a stationary blade extending outwardly from one end of the casing in a direction along the longitudinal axis of the casing, and a generally comb-like movable blade adapted to be reciprocatingly driven relative to the stationary blade. In such electric shaver, a rotary actuator is employed to drive the movable blade and, therefore, a motion translating mechanism is also employed to allow a drive shaft of the actuator to provide a linear motion that is necessary to drive the movable blade.
As far as the electric shaver for use in treatment of the human body hairs, the slimmer and shorter, the more convenient to handle. However, the use of the rotary actuator in combination with the motion translating mechanism as discussed above does not only limit the extent to which the electric shaver can be assembled slim, but also renders the cylindrical casing to have an extra length necessary to accommodate the motion translating mechanism. By way of example, assuming that the rotary actuator is of a type powered by an A-III power cell, disposition of the power cell and the rotary actuator in line with each other within the casing results in the casing increased in length a quantity substantially larger than the width of the palm of a user's hand, which length is further increased when the motion translating mechanism is used.